Interest in epicardial (outer wall of the heart) treatment of ventricular cardiac arrhythmias has grown significantly within electrophysiology. The thickness of the myocardial wall makes it difficult to treat all heart rhythm problems endocardially (from inside the heart). Although early (pre-reperfusion era) data suggested that epicardial ventricular tachycardia (VT) occurred in a minority of patients, recent (non-ischemic VT and rapid reperfusion era) data suggests that about 70% of VT patients have epicardial substrates for the disease. Several studies have suggested that epicardial ablation procedures are not only a viable second line of defense when endocardial methods fail, but that epicardial procedures should be performed in concert with all endocardial treatments to guarantee the greatest probability of treatment success of both ventricular tachycardia (which kills 500,000 Americans per year) and atrial fibrillation (which is the largest cause of strokes in the U.S.). The epicardial surface is also considered to be an important potential therapeutic location for drug and cell delivery and as well as for heart failure therapy.
The ability to gain minimally invasive access to the heart's outer wall for ablation and other therapies has done much to promulgate the adoption of epicardial strategies.
However, conventional types of guidance methods lead to an unacceptable and high risk of perforations of the RV tissue. For instance, Sosa and Scanavacca had an initial perforation rate of 8%, which decreased to 4.5% with experience. Others using this approach have experienced 12% unsuccessful pericardial access, with pericardial effusion in 13 of 35 cases and one death from complications. Still another study suggested that 10 to 20% of all patients undergoing pericardial access for epicardial ablation using the methods described above experienced effusions due to some level of ventricular perforation.
Therefore, it is a goal of an aspect of an embodiment of the present invention to, among other things, improve the method of access and reduce the risks of its use.